Kelly Sotherton retires ahead of London 2012 with back problem

Kelly Sotherton, at the Beijing Games, has announced her retirement from athletics. Photograph: Jason O'Brien/Action Images

Kelly Sotherton has called time on her career two months short of what she had hoped would be a final hurrah at the London Olympics.

The 35-year-old heptathlete had an operation a little over a week ago to remove a piece of disc from her back and although she was told by her doctor she could be running again within six weeks, that does not give her enough time to reach the qualifying standard before the British team is picked.

"I thanked [the doctor] for being optimistic but there's no chance," Sotherton told the Mail on Sunday. "You have to know when to stop."

Sotherton, who returned to the heptathlon last year after quitting it in favour of the 400metres in 2010, was competing at the IAAF Combined Events Challenge in Italy earlier this month when she broke down in the 200metres and said she knew immediately the injury was serious enough to end her dream.

"As soon as it went I knew that was it," she said. "I could hardly walk and could hardly move. At that moment, I said 'It's over'. I cried and I think it was hard for Paula [Clayton, therapist] and Aston [Moore, coach] to see because I was a gibbering wreck.

"I can laugh now. But I was red-faced and it was quite embarrassing leaving the track because I don't want people to see me like that."

Sotherton went to a spinal specialist who told her she needed surgery. "I had already prepared myself for what he would say and that rubber-stamped it," she said. "After that it was, 'OK, it's a relief now'."

Sotherton, a bronze medallist at Athens 2004, said she will now enjoy the Olympics as a fan, and will be supporting Jessica Ennis, insisting that the rivalry between the two had always been misunderstood.

"If Jess was American or French, it wouldn't be so much of a bother but she's British and she was taking my fans," Sotherton said.

"Now I'm happy that she's British and I wouldn't really have meant that a couple of years ago. I'm glad she's doing it. I can watch the event now and get excited. I don't think it's as clear-cut as people think."